使用ghcjs-dom过滤[Node]到[Element]

Question

我使用的是ghcjs-dom。如何从节点数组中筛选出元素？

import GHCJS.DOM.Types

nodesToElements :: [Node] -> [Element]
nodesToElements = ??

或

nodesToElements :: [Node] -> IO [Element]
nodesToElements = ??

Answer 1

import GHCJS.DOM.Types
import Data.Maybe (mapMaybe)

nodeToElement :: Node -> Maybe Element
nodeToElement node = if node `isA` gTypeElement
                     then Just $ castToElement node
                     else Nothing

nodesToElements :: [Node] -> [Element]
nodesToElements = mapMaybe nodeToElement